Severance and Exit Costs (Details) $ in Millions	3 Months Ended
	Jun. 30, 2018 USD ($)
Restructuring Cost and Reserve [Line Items]
Severance Costs	$ 2
Restructuring Charges	8
Wireless [Member]
Restructuring Cost and Reserve [Line Items]
Severance Costs	2
Access [Member] | Severance and exit costs [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Charges	6
Access [Member] | Severance and exit costs [Member] | Wireless [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Charges	1
Access [Member] | Severance and exit costs [Member] | Wireline [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Charges	$ 5